1. Field of the Invention
The present invention generally relates to a propeller guard for use in association with a boat propulsion propeller driven by an outboard motor or an inboard/outboard drive unit. The propeller guard is constructed of injection molded plastic, metal such as aluminum or other metals, fiber reinforced resin plastic or other materials having strength characteristics to provide necessary protection and constructed to minimize hydrodynamic resistance. The propeller guard will protect swimmers and aquatic mammals from coming into contact with the propeller thereby preventing injury and at the same time protect the propeller from damage by engagement with floating or submerged debris.
2. Description of the Prior Art
Propeller guards or shrouds have been developed for use with outboard motors and usually are constructed from metal without concern regarding motor performance and resistance to movement of the guard or shroud through the water. Such devices presently available have proven to be less than totally successful from a use standpoint and from a marketing standpoint in view of the manufacturing processes and added weight of metal guards or shrouds.
The following U.S. patents illustrate developments in this field of endeavor.
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The above prior patents disclose various guard structures for outboard motor propellers including a gridlike structure surrounding the propeller and enabling water flow past and through the propeller guard. However, the above patents do not disclose a structure equivalent to the structure of the propeller guard of the present invention including the particular arrangement of axially spaced, circumferentially extending, concentric rings or bands retained in fixed relation by a unique support spoke structure interconnecting the rings and bands and a unique attachment arrangement for supporting the guard from the cavitation plate and skeg of the propeller drive unit.